Radio frequency communication system and method

ABSTRACT

Method and devices for wirelessly transmitting data packets in a meter reading system, wherein the method comprises generating at the meter device, a first data packet including payload data and a first message authentication code computed based the payload data and associated meter data stored in a memory of the meter device, transmitting the first data packet from the meter device to the receiver, and performing a primary authentication check of the first data packet and verifying the associated meter data at the receiver by recalculating the first message authentication code using the received payload data and current associated meter data stored in a memory of the receiver, as input.

FIELD OF THE INVENTION

The present invention relates to a radio frequency communication systemand method for wirelessly transmitting data packets between twocommunication nodes of a communication network. More specifically theinvention relates to an authenticated encryption scheme for safeguardingvalidity of transmitted data.

BACKGROUND OF THE INVENTION

Automatic meter reading (AMR) systems and advanced meter infrastructure(AMI) systems are generally known in the art. Utility companies use suchsystems to read and monitor consumption meters remotely, typically usingradio frequency (RF) communication. AMR and AMI systems, commonly knownas meter reading systems, increase the efficiency and accuracy ofcollecting readings and managing customer billing.

AMR systems generally use a mobile RF communication network forcollecting meter readings and data, whereas AMI systems use a fixed RFcommunication network. Especially in AMI systems there may be multipleintermediate collectors located throughout a larger geographic area,each collector in turn communicating with a central back end system, forexample by using a wide area network (WAN) or other suitablecommunication infrastructure. An AMI system may also utilize a system ofrepeaters or relay devices that expand the coverage area for each readerby forwarding meter readings and data. In a mobile network AMRenvironment, a handheld, vehicle-mounted, or otherwise mobile readerdevice with RF communication capabilities is used to collect data frommeter devices as the mobile reader is moved from place to place.

A metering system for metering the consumption of a utility may includemeter devices in the form of smart meters provided with communicationdevices for transmitting and receiving RF signals. The communicationdevices may be configured to periodically transmit data packetsincluding data representing multiple meter readings and other meter dataas a function of time. Such data packets are processed, transmitted andrevised by the receiver device according to a communication protocol.

Meter devices are typically battery-powered, and consequently have afinite amount of energy available for their service cycle. Because theservice cycle for meter devices is typically 10-20 years, to reduce costassociated with meter exchange or battery replacement, energyconservation is a major design criterion. For utility meters havingelectrical mains available as a power source, energy conservationrelated to communications may also be desirable.

As radio packet transmission accounts for a substantial portion of theenergy usage in meter devices, more efficient transmission and receptioncan have a significant impact on the energy use, i.e. battery lifetimeof a meter device. Thus, if the power used for transmitting data packetscan be reduced, this will have a positive effect on the total powerbudget of the meter device. One way of reducing transmission power is byreducing the amount of data transmitted and the data packet length.However, transmission power is often closely related to transmissionquality and reception reliability, which is also of great importance.Common grounds for low transmission quality and reliability is pathloss, collision, congestion, etc.

Another important design criterion for utility meter communicationssystems is communication security. A communication system must includemeasures to ensure that data packets transmitted between meter devices,repeaters, collectors and the backend system are authentic and have notbeen tampered with during transmission. Additionally, in manyjurisdictions consumption data is considered personal information.Interception of such data must therefore be prevented to ensure thatunauthorized parties cannot access data.

Meter readings and other data, such as alerts or sensor data, may betransmitted in the form of data packets from the meter devices to thebackend system, and the backend system may transmit data packetsincluding commands or updates, to the meter devices. Reliability has todo with the robustness of the communication system and the ability ofthe system to successfully transmit a data packet from the sender, viapossible intermediate devices, to the correct receiver. If a packet doesnot successfully reach the receiver, it is necessary to retransmit thepacket, which is undesirable.

A need thus exists for an improved communication system wherein thetransmission power is reduced without compromising transmission quality,reception reliability and communication security.

OBJECT OF THE INVENTION

It is an object of the present invention to provide an alternative tothe prior art. In particular, it may be seen as an object of the presentinvention to provide a method for providing secure and effectivecommunication in a smart grid system by reducing the amount of dataneeded to be transmitted.

SUMMARY OF THE INVENTION

Thus, the above described object and several other objects are intendedto be obtained in a first aspect of the invention by providing a method,for wirelessly transmitting data packets from a meter device to areceiver of a meter reading system, the method comprising the steps of:generating at the meter device, a first data packet (DP1) includingconsumption data (CD) as payload data and a first message authenticationcode (MAC1) computed based on a MAC-algorithm using as input the payloaddata (PD), and associated meter data (AMD) and a data encryption key(DEK) stored in a memory of the meter device; transmitting the firstdata packet (DP1) from the meter device to the receiver; performing aprimary authentication check of the first data packet (DP1) at thereceiver by recalculating the first message authentication code usingthe MAC-algorithm with the received payload data (PD), the dataencryption key (DEK) stored in a memory of the receiver, and currentassociated meter data (CAMD) stored in a memory of the receiver, asinput; and accepting the first data packet if it is verified asauthentic.

In this regard, a receiver may be construed as a standalone device suchas a collector- or concentrator of a meter reading system or as anintegrated part of a back end system. Transmission of the data packetsto the receiver may either be directly or indirectly via a number orrelay devices for relaying, retransmitting or forwarding the data packetto the backend system.

Additionally, the meter device may by any kind of device for metering,measuring or sensing a parameter related to the device itself or to someambient condition or change in ambient condition of the device. Themeter device could include means for measuring particle level or thepresence of particles or chemical connection in a substance such as afluid or in the surrounding air.

By applying the above defined communication method, the total packetlength may be substantially reduced, as the payload of the packet isreduced by omitting the associated meter data. However, as theassociated meter data used by the meter must be known to the receiver tocorrectly infer the transmitted consumption data from the informationcontained in a data packet, the defined communication method allows thereceiver to verify the associated meter data.

Moreover, the step of performing the primary authentication of the firstdata packet may further de considered to include an actual verificationof the current associated meter data stored in a memory of the receiveras the first message authentication code is recalculated using theassociated meter data stored by the receiver.

Furthermore, the payload data (PD) may be constituted by the consumptiondata (CD). The consumption data thus being the only payload in the datapacket. The remaining data packet being constituted by overhead data,which may include data to support the type of protocol, employed by thecommunication system and redundancy check data to support detection, andoptionally the correction, of errors caused to the data packet duringtransmission between nodes]

Additionally, if the first data packet is not accepted during theprimary authentication check of the above described method, the methodmay further comprises the steps of: performing a secondaryauthentication check of the first data packet (DP1) at the receiver byrecalculating the first message authentication code using the receivedpayload data PD, the data encryption key DEK and a plurality ofdifferent sets of associated meter data (AAMD) stored in the memory ofthe receiver, as input for the MAC-algorithm; considering the first datapacket as potentially authentic and storing the first data packet in acache memory of the receiver, if one of the different sets of associatedmeter data results in a match for the first message authentication code;generating a second data packet (DP2) at the meter device, includingconsumption data (CD2) as payload data (PD2) and a second messageauthentication code (MAC2), and transmitting the second data packet(DP2) from the meter device to the receiver; performing tertiaryauthentication check of the second data packet (DP2) at the receiver byrecalculating the second message authentication code using theMAC-algorithm with the payload data (PD2), the data encryption key (DEK)and the associated meter data identified during the secondaryauthentication check, as input; accepting the first and the second datapackets as authentic if the recalculation results in a match for thesecond authentication code.

Moreover, the associated meter data may reflect configuration parametersof the meter device, such as unit of measurement, data resolution or anindication of the memory register to be used as input for theconsumption data. Additionally, the current associated data (CAMD) maybe updated if the first and the second data packets are accepted asauthentic during the tertiary authentication check. In addition, thecurrent associated data (CAMD) may initially be inputted into the cachememory of the receiver in connection with the initial installation ofthe meter device our in connection with re-calibration of the meterdevice. Furthermore, the payload data (PD) and the messageauthentication codes of the data packets may be encrypted by the meterdevice before transmission and subsequently decrypted by the receiver.

According to a second aspect of the invention the above described objectand several other objects are intended to be obtained by a meter device(12) for measuring the flow rate of a fluid or for sensing anotherparameter, the meter device comprising: a processor configured tocompute consumption data based on the flow rate measurements or thesensed parameter; a transmitter for transmitting data packets via radiofrequency communication; wherein the processor is further configured toperform the steps of generating and transmitting data packets (DP1,DP2)according to the above described method. Further, the processor maybe part of a processing circuit or a processor and it may be implementedusing discrete components, as an integrated circuit or as an ASIC.

According to a third aspect of the invention the above described objectand several other objects are intended to be obtained by a receiver (14)for receiving a data packet transmitted by a meter device, the receivercomprising means for executing the steps of the method described in anyof the claims 1-6 related to reception of data packets and checking ofauthentication of the received data packets.

According to a fourth aspect of the invention the above described objectand several other objects are intended to be obtained by a radiocommunication protocol comprising instructions to cause the meter deviceand the receiver of claims 7 and 8 to execute the steps of the method ofclaim 1.

The above-described MAC-algorithm may be based on various errordetection schemes such as cyclic redundancy checks (CRCs), checksum, orhamming code. MAC algorithms based on cryptographic methods in generalmay be used as well e.g. algorithms such as CMAC or CBC-MAC based on theAES algorithm or other adequate algorithms. The message authenticationcode (MAC) may also be referred to as a message integrity code (MIC).

Furthermore, as stated above, the payload data (PD) may be constitutedby the consumption data (CD). The consumption data thus being the onlypayload in the data packet. The payload data thus does not include theassociated meter data including the meter identification number, unit ofmeasurement and the measuring resolution. Common to all of theassociated data is that the data is related to configuration parametersof the meter, which are substantially static and thus only changes ifthe meter is intentionally reconfigured. This is contrary to the payloaddata comprising consumption data that inherently changes over time.

BRIEF DESCRIPTION OF THE FIGURES

The method, devices and communication protocol according to theinvention will now be described in more detail with regard to theaccompanying figures. The figures illustrates ways of implementing thepresent invention and is not to be construed as being limiting to otherpossible embodiments falling within the scope of the attached claim set.

FIG. 1 illustrates a meter reading system,

FIG. 2 show diagrams illustrating radio packets, and

FIG. 3 illustrates a meter device.

DETAILED DESCRIPTION OF AN EMBODIMENT

The invention can be implemented by means of hardware, software,firmware or any combination of these. The invention or some of thefeatures thereof can also be implemented as software running on one ormore data processors and/or digital signal processors. The individualelements of an embodiment of the invention may be physically,functionally and logically implemented in any suitable way such as in asingle unit, in a plurality of units or as part of separate functionalunits. The invention may be implemented in a single unit, or be bothphysically and functionally distributed between different units andprocessors.

Referring to FIG. 1, a radio frequency communication system 1 in theform of a meter reading system is illustrated. The meter reading systemcomprises a plurality of meter devices 10 installed at respective pointsof use, configured for transmitting data packets to a receiver 30 viaradio frequency communication. In the shown exemplary meter readingsystem, the receiver is implemented as part of a backend system. Themeter reading system further comprises one or more collector devices 20for communicating with the meter devices via radio frequency (RF)communication, and depending on the geographical distribution of themeter reading system, a 30 number of repeater devices 101 may beincluded to relay data packets from the meter devices to the one or morecollectors. From the collector devices, 20 data packets are transmittedto a backend system 30 either wirelessly or via a cabled connection.Additionally, in an alternative system configuration, a number of mobilecollection devices (not shown) may be included in the system as analternative or supplement to the fixed collector devices. In a one-waycommunication configuration, the meter devices are dedicated transmitterdevices configured for transmitting data packets to the receiver via thecollector devices, and in a two-way communication configuration, each ofthe meter devices, the collector devices and backend system areconfigured to both transmit and receive data packets.

It is understood by the skilled person that other network devices suchas router devices or meter 10 devices equipped with differentcommunication modules may also be included in the above described meterreading system. At least communication between meter devices andcollector and/or repeater devices is based on RF communication, whereasthe transmissions between collector devices and the backend system maybe of any suitable type, such as wired or wireless. Further, it isunderstood by the skilled person that the shown meter reading systemonly includes a limited number of network components for illustrativepurposes.

Referring to FIG. 3, each meter device 10 comprises measuring meansincluding a metering circuit 11 configured to measure the amount of aspecific utility, such as water or electricity, delivered to therespective point of use via the utility network. Based on themeasurements, consumption data CD is computed and stored in a registerof a memory 13 of the meter device. In addition to flow and actualconsumption data, the consumption data may also include other kinds ofdata related to measurements performed by the metering circuit orrelated to the operation of the meter device, such as aggregated flow,flow rate, leakage indication, tamper alarms, ambient temperature.Consumption data in it broadest sense could also encompass measurementperformed by other sensors integrated in the meter device or sensorsoperating as independent devices. In another embodiment (not shown) themeter device may thus be a device for sensing a parameter other thanflow and/or the amount of a utility delivered to a point of use.

Depending on the type of consumption data, the data is stored indifferent registers of the memory 13. The memory 13 also storesassociated meter data AMD reflecting the configuration parameters of themeter device. For example, the associated meter data specifies whichregisters of the memory should be used as input for the data packetsgenerated by the meter device, as will be further described below. Theassociated meter data also includes information about the unit ofmeasurement and the resolution of the data in the register that is usedas input for the generated data packets. The associated meter data AMDis thus data that is necessary to interpret or codify the consumptiondata CD. Without knowing the associated meter data, the consumption datathus cannot be used.

The memory 13 of the meter device further stores a data encryption keysDEK. The data encryption key(s) may be store at the time of initialconfiguration of the meter or loaded into the meter memory at a laterstage, e.g. during an update-session or re-configuration.

During operation, a processing unit 12 of the meter device is configuredto generate data packets DP including the consumption data CD as theonly payload data, as shown in FIG. 2. In addition to the payload, thedata packets include overhead data or redundancy data comprising amessage authentication code MAC. The message authentication code MAC iscomputed by the processing unit 12 based on a MAC-algorithm using thepayload data PD, the associated meter data AMD and the data encryptionkey DEK, as input. The overhead data further includes a packet preambleportion PP, a synchronization portion SP, a packet length field PL. Theoverhead data also includes information about the actual time of thedata packet and the identity of the meter. The data packets thus doesnot include the associated meter data necessary to interpret theconsumption data. For the recipient to make use of the data, theassociated meter data must thus be made available by other means, suchas by prior configuration. By omitting the associated meter data, thesize of the payload of a data packet is substantially reduce, such as by30-50%. As the payload accounts for approximately half the actual packetsize, omission of the associated meter data may reduce total data packetsize about 25%, which again may lead to considerable reductions intransmission power.

Further, the meter device further comprises a transmission circuit 14including an antenna for transmitting the data packets to a receiver ofthe meter reading system. The receiver may be implemented in one or moreof the collector devices 20 or as part of the backend system 30. In thecase of a backend implemented receiver, all meter device of the meterreading system are assigned to the same receiver. In an embodimentwherein the receivers are implemented in the collectors, the meterdevices are divided into sub-groups and assigned to different collectordevices. Further, in one configuration the transmission circuit andantenna may additionally be configured for operating as a receiver forreceiving data packets from the backend system and the collectordevices.

The receiver 20, 30 comprises an associated memory storing dataencryption keys and associated meter data for each of the meter devicesassigned to it. As the associated meter data may change over time, forexample if a meter is replaced or reconfigured, the memory of thereceiver stores a set of current associated meter data CAMD, that isconsidered to be the current valid associated meter data. The receiveris also provided with a processing unit controlling its operation andconfigured to execute the MAC-algorithms also applied by the meterdevices.

When a data packet is received by the receiver, the receiver isconfigured to determine whether the data packet is a valid data packettransmitted from a trusted meter device and whether the data containedin the data packet has been compromised during transmission. To this endthe receiver is configured to perform a primary authentication check ofa received data packet (hereinafter the first data packet DP1). This isdone by the processing unit recalculating the message authenticationcode of the first data packet (hereinafter the first messageauthentication code MAC1) by running the MAC-algorithm using the payloaddata PD included in the first data packet and the stored data encryptionkey DEK and current associated meter data CAMD for the respective meter,as input. If the recalculated first message authentication code isidentical to the first message authentication code received with thefirst data packet, the first data packet is considered authentic andaccepted as valid.

By performing the authentication check using the stored currentassociated meter data CAMD, in addition to determining the authenticityof the full data packet, the receiver also validates the storedassociated meter data. Thus, without actually receiving the associatedmeter data, the receiver ensures that the associated meter data used tointerpret the received consumption data is correct. If the associatedmeter data used by the meter device to generate the messageauthentication code is different from the current associated meter datastored by the receiver, the primary authentication check will fail.

If the first data packet is not considered authentic during the primaryauthentication check, the first data packet is subject to a furthercheck to fully determine validity. Potential tampering or otherfraudulent activities may cause a failed primary authentication check.However, as described above, the authentication check may also fail ifthe current associated meter data stored by the receiver is differentfrom the associated meter data stored in the meter device.

Thus if the primary authentication check fails, a secondaryauthentication check is performed on the first data packet DP1. For thispurpose a plurality of alternative sets of associated meter data AAMDare stored in the memory of the receiver. The alternative sets ofassociated meter data AAMD reflect a limited number of possible meterconfigurations, such as 10-100 different configuration setups. Thesecondary authentication check includes recalculating the first messageauthentication code using the received payload data PD, the dataencryption key DEK and the alternative sets of associated meter dataAAMD as input for the MAC-algorithm. If one of the alternative sets ofassociated meter data AAMD results in a match between the recalculatedmessage authentication code and the received message authenticationcode, the first data packet is considered potentially authentic. Thus,if a match for the first message authentication codes is found, thefirst data packet is considered temporarily valid and stored in a cachememory of the receiver. The receiver further caches the set ofalternative associated meter data set used to deem the first data packetpotentially authentic (in the following referred to as the matchingassociated meter data MAMD).

The receiver then awaits the reception of the next data packet from themeter device (hereinafter the second data packet DP2). The second datapacket is generated at the meter device exactly as the first datapacket. As the second data packet is generated at a later point in time,the payload data PD and the message authentication code included in thesecond data packet has changed. The second data packet thus includespayload data PD2 and a second message authentication code MAC2.

Receiving the second data packet, the receiver first performs theprimary authentication check on the second data packet similar to theprimary authentication check performed on the first data packet, asdescribed above. If second data packet is considered authentic followingthe primary authentication check, i.e. based on the current associatedmeter data, the current associated meter data CAMD stored in thereceiver is considered valid and the second data packet is accepted asvalid. The cached first data packet on the other hand is then rejectedas invalid.

If second data packet is not considered authentic following the primaryauthentication check, the receiver performs a tertiary authenticationcheck. The tertiary authentication check includes checking the secondmessage authentication code MAC2 using the received payload data PD2,the data encryption key DEK and the matching associated meter data MAMDas input for the MAC-algorithm. If the matching associated meter dataMAMD also results in a match for the second message authentication codeMAC2, the receiver accepts both the first and the second data packets asauthentic. However, if using the matching associated meter data MAMD asinput for the MAC-algorithm does not result in a match, i.e. a valueequal to the second message authentication code, both the first datapackets are rejected.

By using this method, it is ensured that the current associated meterdata CAMD is not updated before at least two consecutively received datapackets are considered authentic using the same set of associated meterdata AMD. This has the advantageous effect that the strength of the MACis not weakened by the process in the secondary authentication where anumber of different sets of associated data AMD are used for thecalculations. The strength of the MAC is understood as the probabilitythat when applying the MAC algorithm a change of the authenticated orassociated data will be detected. Thus for a MAC with a high strengththe probability of detecting a change of data is very high.

The ratio of weakening the MAC in the secondary authentication alonewould potentially equal the number of alternative sets of associatedmeter data AAMD. If the number of alternative associated meter data AAMDequals 16 the strength of the MAC will be weakened by a factor of 16which equals reducing the length of the MAC by 4 bits. Thus if themethod would accept a new set of associated meter data based solely onthe secondary authentication check the strength of the authenticitycheck of the system would be less than the inherent strength of the MACdefined by the number of bits in the MAC. Moreover, the weakening wouldbe variable depending on the number of alternative sets of associatedmeter data AAMD, thus the strength of the authentication and integrityof the received data would not be well defined.

Including the tertiary authentication check using only one set ofassociated data (the matching associated meter data MAMD) for theauthenticity check of a new set of payload data PD2, will have theinherent strength of the MAC defined by the number of bits in the MAC.The combined strength of the secondary authentication and the tertiaryauthentication can thus never be less than the inherent strength of theMAC as defined by the number of bits in the MAC.

It is understood by the skilled person that other parts of the datapacket than the payload data PD, the associated meter data AMD and thedata encryption key DEK may be included in the calculation of the MAC ifprotection of these other parts is desired. Such other parts may be butnot limited to one or more elements of overhead data such as meteridentification, packet length, packet type or time information. Further,if the MAC calculation is based on cryptographic methods, such as theAES algorithm or other suitable encryption algorithms, thesecryptographic methods may include an initialization vector. Dataelements to be protected may be included in such an initializationvector. Especially inclusion of the time or a continuous incrementingcounter in the initialization vector may be beneficial to prevent replayof packets.

Although the present invention has been described in connection with thespecified embodiments, it should not be construed as being in any waylimited to the presented examples. The scope of the present invention isto be interpreted in the light of the accompanying claim set. In thecontext of the claims, the terms “comprising” or “comprises” do notexclude other possible elements or steps. In addition, the mentioning ofreferences such as “a” or “an” etc. should not be construed as excludinga plurality. The use of reference signs in the claims with respect toelements indicated in the figures shall also not be construed aslimiting the scope of the invention. Furthermore, individual featuresmentioned in different claims, may possibly be advantageously combined,and the mentioning of these features in different claims does notexclude that a combination of features is not possible and advantageous.

1. A method for wirelessly transmitting data packets from a meter deviceto a receiver of a meter reading system, the method comprising the stepsof: generating at the meter device, a first data packet, DP1, includingconsumption data, CD, as payload data and a first message authenticationcode, MAC1, computed based on a MAC-algorithm using as input the payloaddata, PD, and associated meter data, AMD, and a data encryption key,DEK, stored in a memory of the meter device; transmitting the first datapacket, DP1, from the meter device to the receiver; at the receiver,performing a primary authentication check of the received first datapacket, PD1, and verifying current associated meter data, CAMD, storedin a memory of the receiver by recalculating the first messageauthentication code based on the MAC-algorithm with the received payloaddata, PD, the current associated meter data, CAMD, and the dataencryption key, DEK, stored in a memory of the receiver, as input; andaccepting the first data packet if it is verified as authentic.
 2. Amethod according to claim 1, wherein if the first data packet is notaccepted during the primary authentication check, the method furthercomprises the steps of: performing a secondary authentication check ofthe first data packet, PD1, at the receiver by recalculating the firstmessage authentication code using the received payload data, PD, thedata encryption key, DEK, and a plurality of different sets ofassociated meter data, AAMD, stored in the memory of the receiver, asinput for the MAC-algorithm; considering the first data packet aspotentially authentic and storing the first data packet in a cachememory of the receiver, if one of the different sets of associated meterdata results in a match for the first message authentication code;generating a second data packet, DP2, at the meter device, includingconsumption data, CD2, as payload data, PD2, and a second messageauthentication code, MAC2, and transmitting the second data packet, DP2,from the meter device to the receiver; performing tertiaryauthentication check of the second data packet, DP2, at the receiver byrecalculating the second message authentication code using theMAC-algorithm with the payload data, PD2, the data encryption key, DEK,and the associated meter data identified during the secondaryauthentication check, as input; and accepting the first and the seconddata packets as authentic if the recalculation results in a match forthe second authentication code.
 3. A method according to claim 1,wherein the associated meter data is data reflecting configurationparameters of the meter device, such as unit or measurement, dataresolution or an indication of the memory register to be used as inputfor the consumption data.
 4. A method according to claim 1, wherein thecurrent associated meter data, CAMD, is updated if the first and thesecond data packets are accepted as authentic during the tertiaryauthentication check.
 5. A method according to claim 1, wherein thecurrent associated meter data, CAMD, is initially inputted into thecache memory of the receiver in connection with the initial installationof the meter device in connection with re-calibration of the meterdevice.
 6. A method according to claim 1, wherein the payload data, PD,and the message authentication codes of the data packets are encryptedby the meter device before transmission and subsequently decrypted bythe receiver.
 7. A meter device for measuring the flow rate of a fluidor for sensing another parameter, the meter device comprising: aprocessor configured to compute consumption data based on the flow ratemeasurements or the sensed parameter; and a transmitter for transmittingdata packets via radio frequency communication; wherein the processor isfurther configured to perform the steps of generating and transmittingdata packets, DP1, DP2, according to the method described in claim
 1. 8.A receiver for receiving a data packet transmitted by a meter device,the receiver comprising means for executing the steps of the methoddescribed in claim 1 related to reception of data packets and checkingof authentication of the received data packets.
 9. A radio communicationprotocol comprising instructions to cause the meter device and thereceiver of claim 7 to execute the steps of the method of claim 1.